The present invention relates to an apparatus and method of producing an electronic device by applying dry etching, sputtering CVD, or another process in a chamber.
Recently, along with the high density or high integration of electronic devices, there has been a growing demand for high level processing precision. Therefore, when dry etching, sputtering CVD, or another process is applied during the production of LSI where a large number of transistors are integrated or a liquid crystal device where a large number of elements such as TFT are integrated, a workpiece to be processed is placed inside the chamber, so as to secure an atmosphere necessary for applying the process and a clean atmosphere with few particles.
A conventional apparatus and method of producing an electronic device will be described by taking the case of a conventional dry etching process.
FIG. 10 is a plasma apparatus disclosed in Japanese Laid-open Patent Application No. 6-196421 which makes use of an electron cyclotron resonance (ECR).
As shown in FIG. 10, in a plasma creation room 101 provided with a microwave introduction window 101a and a plasma drawing window 101b, a bell jar 104 is provided which has been subjected to a surface-roughening process with a frost treatment. A sample room 103 which has a table 108 for placing a sample S thereon is adjacently connected with the plasma creation room 101, and further connected with a gas introduction tube 109 and an evacuation tube 111. An anti-adhesive plate 105 is provided along the sample room 103, the table 108, and one end of the evacuation tube 111. Top heating walls 106a and 106b and bottom heating walls 107a and 107b are provided on the side wall of the plasma creation room 101, the side and lower walls of the sample room 103, and the outer surface of one end of the evacuation tube 111, respectively. An excitation coil 112 is provided along the circumference of a top heating wall 106 and one end of a wave guide 102 which is connected with the plasma creation room 101. A heated liquid is circulated along the top heating walls 106a and 106b and the bottom heating walls 107a and 107b, so as to heat the bell jar 104 and the anti-adhesive plate 105, thereby applying a plasma treatment to the sample S. The inner surfaces of the bell jar 104 and the anti-adhesive plate 105 have been subjected to a surface-roughening process.
Thus, a surface-roughening process used to be applied exclusively to the inner surface of the anti-adhesive plate 105. However, considering that the falling of products (deposits) occurs in the bell jar 104, too, the surface roughening process is also applied to the inner surface of the bell jar 104, so as to enhance the effect of adhering products as deposits, which result from a plasma treatment or the like, onto the inner surface which has been subjected to the surface roughening process. Consequently, the adhesion of the products onto the inner surface of the bell jar 104 is enhanced, and the falling of the products is restricted, so that the number of particles which adhere onto the sample S is reduced.
However, the above-mentioned conventional plasma apparatus has the following problem because the function of the apparatus after cleaning is conducted when the apparatus has been used for a certain time period is not taken into consideration.
For example, in order to remove products containing silicon from a quartz bell jar whose inner surface has an average surface roughness Ra of 10 .mu.m, the bell jar must be immersed in a 1% aqueous solution of fluoric acid for about an hour under ultrasonic. However, the immersion of the bell jar in the aqueous solution of fluoric acid for such a long time period under ultrasonic causes the inner surface itself of the quartz bell jar to be etched and the inner surface which has been subjected to the surface roughening process to become more even. As a result, the function of enhancing the adhesion of the products onto the inner surface of the bell jar or the like is deteriorated after the bell jar is cleaned. In order to maintain the function of enhancing the adhesion of the products, the surface roughening process must be applied every time the quartz bell jar is cleaned. Such a troublesome process exhausts the quartz bell jar, making it unusable.
After having examined the conditions of unevenness of the inner surface which are needed to maintain the function of enhancing the adhesion of deposits such as a quartz member after cleaning, the inventors of the present invention have found that the average surface roughness Ra of the inner surface is more important than the maximum surface roughness Rmax of the inner surface. To be more specific, the maximum surface roughness Rmax indicates the difference between the peak value and the trough value in a comparatively wide range in the lateral direction. In the meanwhile, the average surface roughness Ra indicates the average size of unevenness in a minute range in the lateral direction. The easiness of removing deposits depends on how deep the deposits are engaged in the concave portions in the minute range. In contrast, according to the prior art including the above-mentioned Japanese Laid-open Patent Application, there is no consideration about how the average surface roughness Ra is dealt with in order to maintain the function of enhancing the adhesion of deposits after cleaning. Therefore, there is a fear that the effects may not be maintained after the apparatus is cleaned every time it is used for a certain time period.